The promise of gene therapy has the potential to drastically limit the impact of human disease by altering the make-up of the body’s cells to fight back against deadly invaders. If used recreationally, though, gene therapy could also expand the physical limits of human strength and endurance. Like high-tech steroids, gene therapies could one day be a new way for athletes to dope.

Hoping to preemptively limit the consequences of the rapidly advancing field of genetic engineering in sports, the World Anti-Doping Agency officially added genetic engineering to its black list of banned substances and methods earlier this month. Beginning next year, the updated list will include “gene editing agents designed to alter genome sequences and/or the transcriptional or epigenetic regulation of gene expression.”

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“Gene editing technology has advanced impressively in recent years,” WADA, an independent international agency which influences anti-doping polices at the Olympics and in nations around the world, told Gizmodo in a statement. “This has prompted WADA to evaluate possible misuses of gene editing for doping and as a consequence, has included these technologies in the definition of Gene Doping.”

For years, researchers and sports officials have been asking questions about how advancing science might impact sport. It makes sense. Already advances in technology are relied upon to help give athletes a millisecond edge over their competitors. Sometimes that technology is biomedical in nature. The NBA’s Golden State Warriors, for example, have been known to rely on possibly psuedoscientific brain-zapping to give them an edge.

There have been no confirmed accounts of gene doping so far in sports, but the possibility has long been on WADA’s radar. In 2003, the agency officially banned “gene doping.” The update expands that ban to include any form of gene editing, crushing the possibility of any justified use of such medical technologies in sports, even if they one day become more commonplace in other areas of life.

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“Despite sensational and scientifically unfounded claims occasionally seen in the media, WADA is not presently aware of any athletes who are gene doping,” the agency said via email. “Nevertheless we want to be ahead of the game and make it clear that when or if such techniques as gene editing would be used to enhance performance beyond a return to normal function, then it would be prohibited.”

It is unclear, however, how WADA would enforce such rules. For more than a decade, the agency began looking for a way to detect gene doping among athletes. Last year, the International Olympic Committee announced that athletes competing in Rio would be tested for added copies of a gene that produces a hormone called EPO that stimulates red blood cell production to increase endurance. No results have been announced, but such small tweaks could be hard to detect.

The agency declined to provide details on how it planned to enforce the new rules.

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“At present, WADA is closely following developments in this area to define the best technique for the detection of gene editing if and when it were to be used as a doping method,” the agency said.